What is then name of the rap song that has little kids in the background singing lalalalalala and has a man with a lot of bass in his voice saying throw your hands up?

The song you're thinking of is "Lollipop" by Lil Wayne. It features a catchy chorus with children singing "lalalalalala" and has a deep bass voice saying phrases like "throw your hands up." The track was a major hit and is known for its playful yet provocative lyrics.